Douglas S. Galvao

Douglas S. Galvao
University of Campinas | UNICAMP · Departamento de Física Aplicada (DFA)

Ph. D.

About

479
Publications
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Publications

Publications (479)
Preprint
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In the last decade, the materials community has been exploring new 2D materials (graphene, metallene, TMDs, TMCs, MXene, among others) that have unique physical and chemical properties. Recently, a new family of 2D materials, the so-called 2D silicates, have been proposed. They are predicted to exhibit exciting properties (such as high catalytic ac...
Preprint
In this work, we investigated the effect of knots in the thermal transport of graphene nanoribbons through non-equilibrium molecular dynamics simulations. We considered the cases of one, two, and three knots are present. Temperature jumps appear in the temperature profile where the knots are located, which indicates that they introduce thermal resi...
Preprint
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In this work, we investigated the mechanical response and fracture dynamics of boron nitride nanotubes (BNNTs)-peapods under ultrasonic velocity impacts (from 1 km/s to 6 km/s) against a solid target. BNNT-peapods are BNNTs containing an encapsulated linear arrangement of C60 molecules. We carried out fully atomistic reactive (ReaxFF) molecular dyn...
Preprint
Carbon nanoscrolls (CNSs) are nanomaterials with geometry resembling graphene layers rolled up into a spiral (papyrus-like) form. Effects of hydrogenation and temperature on the self-scrolling process of two nanoribbons interacting with a carbon nanotube (CNT) have been studied by molecular dynamics simulations for three configurations: (1) graphen...
Article
The discovery of novel materials that are stable at ambient conditions with emergent functionalities is a pressing need of the 21st century to keep the pace of social and technological advancement in a sustainable manner. Nanotechnology and nanomaterials are one of this kind and the current era has already witnessed several groundbreaking discoveri...
Preprint
New monolayer 2D carbon structures, namely qHPC60 and qTPC60, were recently synthesized by covalently bonding C60 polymers. Here, we carried out Reactive (ReaxFF) molecular dynamics simulations to study the thermodynamic stability and fracture patterns of qHPC60 and qTPC60. Our results showed that these structures present similar thermal stability,...
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A quasi-2D semiconductor carbon allotrope called tetrahexcarbon, also named tetragraphene, was recently proposed featuring an unusual structure combining squared and hexagonal rings. Mechanical and electronic properties of tetragraphene have been predicted based on first-principles Density Functional Theory (DFT) calculations. However, a comprehens...
Preprint
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Studies aimed at designing new allotropic forms of carbon have received much attention. Recently, a new 2D graphene-like allotrope named Pentahexoctite was theoretically proposed. Pentahexoctite has a metallic signature, and its structure consists of continuous 5-6-8 rings of carbon atoms with sp2 hybridization. Here, we carried out fully-atomistic...
Preprint
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Closely packed quasi-hexagonal and quasi-tetragonal crystalline phase of C$_{60}$ molecules (named qHPC$_{60}$) was recently synthesized. Here, we used DFT simulations to investigate the electronic, optical, and mechanical properties of qHPC$_{60}$ monolayers. qHPC$_{60}$ has a moderate direct electronic bandgap, with anisotropic mechanical propert...
Article
Green Energy In article number 2201667, Douglas S. Galvao, Partha Kumbhakar, Chandra Sekhar Tiwary, and co‐workers convert dust crystals of biotite ores from mountains into atomically thin two‐dimensional materials using liquid exfoliation. Two‐dimensional‐biotite can be utilized to harvest small force/pressure or strain for generating green electr...
Article
Closely packed quasi-hexagonal and quasi-tetragonal crystalline phase of C60 molecules (named qHPC60) was recently synthesized. Here, we used GGA-PBE based DFT simulations to investigate the optoelectronic and mechanical properties of qHPC60 monolayers. qHPC60 has a moderate direct electronic bandgap, with anisotropic mechanical properties. Their e...
Article
In this work, the synthesis and characterization of ultrathin metal oxide, called biotene, using liquid‐phase exfoliation from naturally abundant biotite are demonstrated. The atomically thin biotene is used for energy harvesting using its flexoelectric response under multiple bending. The effective flexoelectric response increases due to the prese...
Article
The concept of a diode is usually applied to electronic and thermal devices but very rarely for mechanical ones. A recently proposed fracture rectification effect in polymer-based structures with triangular void defects has motivated us to test these ideas at the nanoscale using graphene membranes. Using fully-atomistic reactive molecular dynamics...
Article
Full-text available
Magnetism in semiconductor two-dimensional (2D) materials is gaining popularity due to its potential applications in memory devices, sensors, spintronics, and biomedical applications. Here, 2D cobalt telluride (CoTe) has been synthesized from its bulk crystals using a simple and scalable liquid-phase exfoliation method. The ultrathin CoTe shows ~ 4...
Article
Two-dimensional (2D) materials have been shown to be efficient in energy harvesting. Here, we report the use of waste heat to generate electricity via the combined piezoelectric and triboelectric properties of 2D cobalt telluride (CoTe2). The piezo-triboelectric nanogenerator (PTNG) produced an open-circuit voltage of ∼5 V under 1 N force and the e...
Article
Full-text available
At the molecular scale, bone is mainly constituted of type-I collagen, hydroxyapatite, and water. Different fractions of these constituents compose different composite materials that exhibit different mechanical properties at the nanoscale, where the bone is characterized as a fiber, i.e., a bundle of mineralized collagen fibrils surrounded by wate...
Preprint
The concept of the diode is usually applied to electronic and thermal devices but very rarely for mechanical ones. A recently proposed fracture rectification effect in polymer-based structures with triangular voids defects has motivated us to test these ideas at the nanoscale using graphene membranes. Using fully-atomistic reactive molecular dynami...
Article
The surface functionalization of diamonds has been extensively studied through a variety of techniques, such as controlled oxidation. Several oxygen groups have been detected on oxidized diamonds, such as C–O–C (ester), C=O (ketonic), and C–OH (hydroxyl). However, the composition and relative concentration of these groups on diamond surfaces can be...
Article
Recently, a new two-dimensional carbon allotrope named biphenylene network (BPN) was experimentally realized. The BPN structure consists of four-, six-, and eight-membered rings of sp2-hybridized carbon atoms. In this work, we carried out fully-atomistic reactive (ReaxFF) molecular dynamics simulations to study the mechanical properties and fractur...
Preprint
The surface functionalization of diamond has been extensively studied through a variety of techniques, such as oxidation. Several oxygen groups have been correspondingly detected on the oxidized diamond, such as COC (ester), CO (ketonic), and COH (hydroxyl). However, the composition and relative concentration of these groups on diamond surfaces can...
Article
Quasicrystals (QCs) are intermetallic materials with long-range ordering but with lack of periodicity. They have attracted much interest due to their interesting structural complexity, unusual physical properties, and varied potential applications. The last four decades of research have demonstrated the existence of different forms of QC composed o...
Article
Full-text available
Hexagonal boron nitride (hBN) has received much attention in recent years as a two-dimensional (2D) dielectric material with potential applications ranging from catalysts to electronics. hBN is a stable covalent compound with a planar hexagonal lattice and is relatively unreactive to most chemical environments, making the chemical functionalization...
Article
Hydrogenated diamond has been regarded as a promising material in electronic device applications, especially in field-effect transistors (FETs). However, the quality of diamond hydrogenation has not yet been established, nor has the specific orientation that would provide the optimum hydrogen coverage. In addition, most theoretical work in the lite...
Article
Carbon nano-onions (CNO) are multilayered fullerenes. They exhibit good electrical conductivity and large surface area, being of interest for several optoelectronic applications. However, it is still an open question what synthesis routes can be used to convert them into diamonds. Here, we used fully atomistic reactive (ReaxFF) molecular dynamics s...
Article
Pentadiamond is a recently proposed new carbon allotrope consisting of a network of pentagonal rings where both sp² and sp³ hybridization are present. In this work we investigated the mechanical and electronic properties, as well as, the thermal stability of pentadiamond using DFT and fully atomistic reactive molecular dynamics (MD) simulations. We...
Preprint
Nature-occurring structures exhibiting unique topological features such as complex and gradient porosity has been the basis to create new materials and/or structures. Most studies have been focused on complex periodic porous structures but gradient porous ones have not been yet fully investigated for stable structural designs. In this work, we have...
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Full-text available
Heterostructure materials form the basis of much of modern electronics, from transistors to lasers and light-emitting diodes. Recent years have seen a renewed focus on creating heterostructures through the vertical integration of two-dimensional materials, including graphene, hexagonal boron nitride, and transition metal dichalcogenides (TMDCs). Ho...
Article
A new auxetic (negative Poisson’s ratio values) structure based on a γ-graphyne structure, here named AγG structure, is proposed. The AγG structural/mechanical and electronic properties, as well as its thermal stability, were investigated using classical reactive and quantum molecular dynamics simulations. AγG is shown to have a bandgap larger than...
Preprint
Full-text available
Recently, a new two-dimensional carbon allotrope, named biphenylene network (BPN) was experimentally realized. The BPN structure is composed of four-, six-, and eight-membered rings of sp$^2$-hybridized carbon atoms. In this work, we carried out fully-atomistic reactive (ReaxFF) molecular dynamics simulations to study the thermomechanical propertie...
Preprint
Full-text available
Carbon nano-onions (CNO) are multi-shell fullerenes. In the present work, we used fully atomistic reactive (ReaxFF) molecular dynamics simulations to study the dynamics and structural transformations of CNO structures under high-velocity impacts against a fixed and rigid substrate. We considered single and multi-shell CNO (up to six shells) and at...
Preprint
In this work, we propose a new auxetic (negative Poisson's ratio values) structure, based on a $\gamma$-graphyne structure, here named $A\gamma G$ $structure$. Graphynes are 2D carbon allotropes with phenylic rings connected by acetylenic groups. The A$\gamma$G structural/mechanical and electronic properties, as well as its thermal stability, were...
Preprint
Full-text available
Magnetism in semiconductor two-dimensional (2D) materials is gaining popularity due to its potential application in memory devices, sensors, spintronic and biomedical applications. Here, 2D Cobalt Telluride (CoTe) has been synthesized from its bulk crystals using a simple and scalable liquid-phase exfoliation method. The atomically thin CoTe shows...
Preprint
Full-text available
Two-dimensional (2D) materials have been shown to be efficient in energy harvesting. Here, we report utilization of waste heat to generate electricity via combined piezoelectric and triboelectric property of 2D Cobalt Telluride (CoTe2). The piezo-triboelectric nanogenerator (PTNG) produced an open-circuit voltage of ~5V under 1N force and the effec...
Article
Polymer-based materials exhibit a good combination of strength and ductility but limited flexural strength. Here we demonstrate a family of new zeolite templated interconnected carbon nanotubes like porous networks with unique topologies with enhanced load-bearing and energy-absorbing capabilities. The structures were initially obtained from fully...
Article
Two-dimensional (2D) materials are at the forefront of current materials research due to their exciting and unique properties. 2D tellurides are emerging materials which are yet to be fully explored. To provide an overview of this emergent field, in this review, we discuss the structure, properties, synthesis methods, and applications of selected 2...
Article
Full-text available
Additive manufacturing allows to produce parts with complex geometries is an essential tool in materials science. Schwarzites is a class of carbon allotropes with interesting mechanical properties. However, most of the schwarzite studies are theoretical until now because the synthesis of large schwarzite fragments remains elusive. In this work, we...
Article
Locating and manipulating nano‐sized objects to drive motion is a time and effort consuming task. Recent advances show that it is possible to generate motion without direct intervention, by embedding the source of motion in the system configuration. In this work, an alternative manner to controllably displace nano‐objects without external manipulat...
Article
Full-text available
Carbon nanoscrolls (CNSs) are nanomaterials with geometry resembling graphene layers rolled up into a spiral (papyrus-like) form. Effects of hydrogenation and temperature on the self-scrolling process of two nanoribbons interacting with a carbon nanotube (CNT) have been studied by molecular dynamics simulations for three configurations: (1) graphen...
Article
Oxygen bonded with diamond surfaces impacts important properties such as electrical conductivity, Schottky barrier height, field emission, and chemical reactivity. Though processes such as thermal, hydrogen plasma, etc., are efficient in oxidizing the hydrogen-terminated diamond surfaces, the oxidation of pristine diamond surfaces through wet chemi...
Article
Full-text available
The impact of micro and nanoplastic debris on our aquatic ecosystem is among the most prominent environmental challenges we face today. In addition, nanoplastics create significant concern for environmentalists because of their toxicity and difficulty in separation and removal. Here we report the development of a 3D printed moving bed water filter...
Article
It is known that surface terminations contribute significantly to diamond properties. As one of the most commonly studied types, oxygen-terminated diamond surface possesses a positive electron affinity (PEA) and hydrophilicity, making it suitable for electronic device fabrication and bioapplications. Various oxidation methods have been reported on...
Preprint
Full-text available
Hydrogenated diamond has been regarded as a promising material in electronic device applications, especially in field-effect transistors (FETs). However, the quality of diamond hydrogenation has not yet been established, nor has the specific orientation that would provide the optimum hydrogen coverage. In addition, most theoretical work in the lite...
Preprint
In this work, We combined fully atomistic molecular dynamics and finite elements simulations with mechanical testings to investigate the mechanical behavior of atomic and 3D-printed models of pentadiamond. Pentadiamond is a recently proposed new carbon allotrope, which is composed of a covalent network of pentagonal rings. Our results showed that t...
Article
Recently, it was experimentally shown that the performance and thermal stability of the perovskite MAPbI3 were improved upon the adsorption of a molecular layer of caffeine. In this work, we used a hybrid methodology that combines uncoupled monte carlo (UMC) and density functional theory (DFT) simulations to carry out a detailed and comprehensive s...
Preprint
Full-text available
Pentadiamond is a recently proposed new carbon allotrope consisting of a network of pentagonal rings where both sp$^2$ and sp$^3$ hybridization are present. In this work we investigated the mechanical and electronic properties, as well as, the thermal stability of pentadiamond using DFT and fully atomistic reactive molecular dynamics (MD) simulatio...
Preprint
Full-text available
Carbon nanoscrolls (CNSs) are nanomaterials with geometry resembling graphene layers rolled up into a spiral (papyrus-like) form. We used fully-atomistic reactive (ReaxFF) MD simulations to investigate the hydrogenation effects on the self-scrolling process of graphene and graphane (hydrogenated graphene) nanoribbons interacting with a CNT. We have...
Article
An easily scalable fabrication method has been explored to obtain atomically thin gallium telluride (GaTe), which opens up new prospective applications of this well-known material. Due to nanostructuring, the optical and electrochemical properties of 2D GaTe at room temperature see remarkable improvements. The effects of surface defects on the opti...
Preprint
Full-text available
Locating and manipulating nano-sized objects to drive motion is a time and effort consuming task. Recent advances show that it is possible to generate motion without direct intervention, by embedding the source of motion in the system configuration. In this work, we demonstrate an alternative manner to controllably displace nano-objects without ext...
Article
Membranes of carbon allotropes comprised solely of densely packed pentagonal rings, known as penta-graphene, exhibit negative Poisson’s ratio (auxetic behavior) and a bandgap of 3.2 eV. In this work, we investigated the structural stability, mechanical and fracture properties of nanotubes formed by rolling up penta-graphene membranes, the so-called...
Article
A reciprocal structure (RS) is a mechanical resistant structure formed by a set of self-supporting elements satisfying certain conditions of structural reciprocity (SR). The first condition is that each element of the structure has to support and be supported by the others. The second condition is that these functions cannot occur in the same part...
Article
Recently, laser-assisted chemical vapor deposition was used to synthesize a free-standing, continuous, and stable monolayer amorphous carbon (MAC). MAC is a pure carbon structure composed of randomly distributed five, six, seven, and eight atom rings, which differs from disordered graphene. More recently, amorphous MAC-based nanotubes (a-CNT) and n...
Article
Free-standing monolayer amorphous carbon (MAC) is a pure carbon structure composed of randomly distributed atom rings with different sizes, which was recently synthesized. In this work, we carried out ab initio and tight-binding calculations to investigate the optoelectronic properties of MAC and its derived nanotube and nanoscroll configurations....
Preprint
Full-text available
A thorough investigation of local structure, influencing macroscopic properties of the solid is of potential interest. We investigated the local structure of GaN nanowires (NWs) with different native defect concentration synthesized by the chemical vapor deposition technique. Extended X-ray absorption fine structure (EXAFS) analysis and semi-empiri...
Article
Carbon‐based tubular materials have sparked a great interest in future electronics and optoelectronics device applications. In this work, we computationally studied the mechanical properties of nanotubes generated from popgraphene (PopNTs). Popgraphene is a 2D carbon allotrope composed of $5‐8‐5$ rings. We carried out fully atomistic reactive (Reax...
Chapter
Low-dimensional atomic layered structures have gained much attention due to their fascinating properties such as surface area, mechanical properties, chemical inertness, conductivity, etc. However, to integrate these outstanding materials into the today’s technology, their structures need to be modified. One of the paths that can be used to integra...
Preprint
Full-text available
Recently, laser-assisted chemical vapor deposition was used to synthesize a free-standing, continuous, and stable monolayer amorphous carbon (MAC). MAC is a pure carbon structure composed of randomly distributed five, six, seven, and eight atom rings, which differs from disordered graphene. More recently, amorphous MAC-based nanotubes (a-CNT) and n...
Article
Organic polymers are promising materials for the design of active layers of chemical sensors. In this context, polyfuran (PF) derivatives have not been largely investigated, mainly due to stability problems and poorer electrical properties. Recent works have demonstrated that some of these typical drawbacks can be overcome by an appropriate choice...
Article
Recently, a new two-dimensional carbon allotrope called Penta-graphene membrane was proposed. The Penta-graphene membrane exhibits interesting mechanical and electronic properties, including typical band gap values of semiconducting materials. Penta-graphene has a Cairo-tiling-like 2D lattice of non coplanar pentagons and its mechanical properties...
Article
Recently, a new 3D carbon allotrope named pentadiamond was proposed composed by mixed sp2 and sp3-like hybridization. In this work, we have carried out a detailed investigation of the electronic, optical and thermoelectric properties of pentadiamond structure using first-principles methods. Our results show that pentadiamond has an indirect bandgap...
Preprint
Full-text available
Carbon-based tubular materials have sparked a great interest for future electronics and optoelectronics device applications. In this work, we computationally studied the mechanical properties of nanotubes generated from popgraphene (PopNTs). Popgraphene is a 2D carbon allotrope composed of $5-8-5$ rings. We carried out fully atomistic reactive (Rea...
Preprint
Two-dimensional (2D) magnetism has been highly sought after since the discovery of graphene, the first and most studied of all the 2D materials. However, experimental evidence for ferromagnetic ordering in isotropic 2D crystals has been missing until a three-atoms thick CrI3 was shown to retain ferromagnetic ordering at finite temperatures down to...
Article
Due to the wide range of possible applications, atomically thin two-dimensional heterostructures have attracted much attention. In this work, using first-principles calculations, we investigated the structural and electronic properties of planar AlN/GaN hybrid heterojunctions with the presence of vacancies at their interfaces. Our results reveal th...
Preprint
Full-text available
Recently, a new carbon 3D carbon allotrope named pentadiamond was proposed. Pentadiamond is composed of carbon atoms in mixed sp$^2$ and sp$^3$-like hybridization. In this work, we have carried out a detailed investigation of the electronic and optical properties of pentadiamond structure using first-principles (DFT) methods. Our results show that...
Article
Zeolite-templated carbons (ZTC) are structures synthesized via chemical vapor deposition of precursors inside sacrificial zeolites, with diverse applications. In spite of the interest in ZTC, little is known regarding their mechanical properties. Here, we investigate the thermal and mechanical behaviors of three-dimensional beta zeolite-templated c...